Chicago mayor Richard Daley, in Hong Kong on the last leg of a China tour, said yesterday the Midwestern metropolis aspires to be the 'most friendly city in the United States for Chinese investors and tourism'.

Daley, who will retire in May after 22 years in office, said he visited an electric car and bus factory in Hangzhou, and a Motorola plant in Tianjin, but offered no details of business talks on the tour, during which he launched his 'Chicago-China Friendship Initiative'.

Nearly 300 Chicago-based firms have operations on the mainland, including Motorola, Wrigley and Boeing. The Chicago area is home to 30 mainland-owned firms.

Daley, a Democrat, is a key figure in promoting Chicago's ties with China. He said President Hu Jintao's visit to the city during his US tour in January - his only stop outside Washington - was 'very significant'. More than 500 guests attended a dinner he hosted for Hu. On the mainland, Daley sought both state and private investors for a high-speed rail link from Chicago's city centre to O'Hare International Airport, but he declined to discuss details. 'China has the experience and expertise; we're trying to work it out.'

Asked what he thought Chicago could bring to its relations with China beyond business and investment, Daley pointed to various exchange programmes, including some between universities and high schools, and some in government, environment and construction.

Chicago also boasts America's biggest Putonghua-teaching programme, with more than 20,000 children learning Chinese in the public school system, Daley said. 'It's very important for us, as a global city, to give our young people a better understanding of the world and better opportunities,' he said.

Daley has been criticised for avoiding human rights issues when dealing with China, but he defended himself by saying he often held talks in confidence. He declined to elaborate. 'I've always talked about human rights... but I'm not here to debate about the whole world. [It's] not my role; my role is to keep peace and harmony between people.'